Article Metrics

Abstract

This study was focused on production and utilisation of laccase in pulp bleaching process. Laccase was produced by white-rot fungi of Marasmius sp which was immobilised in luffa sponge in a modified immersion bioreactor. The Experiment was conducted to study the effect of variation of immersion periods in the production of laccase. The immersion periods applied in this study were 15 minutes, 12 hours and 24 hour respectively. Lacase was then utilised in pre-treatment of pulp bleaching of Accacia mangium unbleached-pulp. The bleaching process were conducted with and without addition mediator of 2,2'-azinobis 3-ethylbenzthiazoline-6-sulphonic acid (ABTS) which has ability to enhance the delignification process.
The results showed that immersion period of 12 hours exhibited the highest maximum laccase activity. Maximum level of laccase attained from culture with 12 hours immersion period was 457.6 U/L. When the immersion period be double ( 24 hours), the level of laccase, however, becoming lower i.e. 281.9 U/L. A 15 minutes immersion period has resulted in a level of laccase of 384.4 U/L. Utilisation of crude enzymes by addition of ABTS mediator with enzyme exposure time 6 hours at temperature of 45^oC has increased brightness for 2.8 points. Pretreatment in similar conditions with no ABTS has added showed an increase in brightness for 0.7 point. It demonstrated that the addition  of ABTS has improved biobleaching process. The pulp exposed to crude enzymes for 6 days at room temperature has increased the brightness of pulp to 5.3 points. These results indicate that laccase has a potential ability  in pulp bleaching process.

Keywords: a modified temporary immersion bioreactor, bleaching, brightness\, crude enzyme, laccase, luffa, Marasmius sp., white-rot fungi.




INTISARI

Penelitian ini ditujukan untuk memproduksi lakase dan menggunakannya dalam proses pemutihan pulp. Produksi lakase dilakukan dengan menggunakan jamur pelapuk putih Marasmius sp. yang diimobilisasi pada bulustru. Bioreaktor yang digunakan adalah bioreaktor imersi berkala termodifikasi. Penelitian produksi lakase dilakukan dengan variasi waktu imersi 15 menit, 12 jam dan 24 jam. Produk berupa ekstrak kasar lakase digunakan sebagai perlakuan awal proses pemutihan pulp Acasia mangium. Pemutihan pulp dilaksanakan dengan dan tanpa mediator 2,2'-azinobis 3-ethylbenzthiazoline-6-sulphonic acid (ABTS) yang berfungsi untuk meningkatkan proses delignifikasi.
Hasil penelitian menunjukkan bahwa waktu immersi 12 jam menghasilkan lakase dengan aktivitas paling tinggi yaitu mencapai 457,6 U/L, lebih tinggi dibandingkan waktu immersi 15 menit (348,4 U/L) dan waktu imersi 24 jam (281,9 U/L). Pemutihan pulp menggunakan ekstrak kasar lakase dengan bantuan ABTS selama 6 jam dan suhu 45^oC  dapat meningkatkan derajat putih sebesar 2,8 poin. Sedangkan pada kondisi yang sama namun tanpa penambahan ABTS hanya dapat meningkatkan derajat putih 0,7 poin. Hal ini menunjukkan bahwa penggunaan ABTS dapat meningkatkan proses pemutihan. Sementara penggunaan ekstrak kasar lakase selama enam hari dapat meningkatkan derajat putih sebesar 5,3 poin. Dengan demikian, lakase memiliki potensi untuk peningkatan derajat putih proses pemutihan pulp yang diharapkan dapat mengurangi kebutuhan bahan kimia pemutih dan mengurangi limbah berbahaya proses pemutihan.

Kata kunci: bioreaktor imersi berkala termodifikasi, pemutihan, derajat putih, ekstrak kasar, lakase, bulustru, Marasmus sp., jamur pelapuk putih.